Apparatus and method for spent solvent collection

ABSTRACT

An apparatus and method are provided for use in removal of coatings from airplanes and the like wherein such removal requires the application of a solvent composition for dissolving the coating such as paint, the solvent having a sufficiently high vapor pressure to be present in both a liquid phase and a gaseous vapor phase at stripping temperatures with the solvent in the vapor phase being lighter than the liquid phase and heavier than air, and the apparatus including a portable carriage, positionable beneath the airplane, a receptacle having spaced side walls and carried by the carriage, the side walls extending vertically upwardly, the receptacle further defining a receptacle bottom portion, the receptacle receiving spent solvent in both the liquid and the vapor phases after application of the solvent to the airplane surfaces and dissolution of the paint therein, the side walls directing the received spent solvent in both phases to the receptacle bottom portion such that vapor phase is trapped above the heavier liquid phase by the lighter air thereover, and an exhaust port located above the receptacle bottom portion for removing the vapor phase.

TECHNICAL FIELD

The present invention is related generally to a system for collectingspent solvent during the removal of coatings such as paint from largeobjects, and particularly to an apparatus, system and method for useduring the removal of paint from airplanes.

BACKGROUND ART

The removal of paint from large objects such as airplanes and the likeposes inherent dangers to the workers involved, as well as to thesurrounding environment. Generally, the surfaces of the airplane aresprayed with paint remover (stripper) in a maintenance hangar with largefans employed to drive away, or at least reduce the concentration of,toxic fumes generated during the stripping operation. Although theworkers involved in the paint removal operation typically wearprotective clothing such as gloves and gas masks, workers in other areasof the hangar working on other jobs are usually not so protected and areplaced at risk by exposure to the contaminated fumes.

Further, in such stripping operations, liquid paint remover is generallyallowed to run onto the floor, not only posing health risks to theworkers in the hangar, but also to the surrounding land and ground waterfrom run-off and drainage. Additionally, such spent liquid paint removerbecomes sticky with the components of stripped paint dissolved therein.Thus, the job of removing paint from airplanes generally involves twojobs, stripping of the paint from the airplane and then clean-up of thespent paint remover from the hangar floor, both of which pose serioushealth risks to the workers involved.

One example of a prior art device for the removal of surface coatingssuch as paint from the surfaces of large objects is disclosed in U.S.Pat. No. 1,842,099 to Johnson which describes a portable unit with aseries of lines for pumping a heated solvent into a pipe networksurrounding the object to be treated, such pipes including perforationsfor spraying the hot cleanser onto the object. Gutters are positioned atlower edges of the object for receiving spent solvent. Drainage pipesand lines return the liquid solvent to the portable unit where it isfiltered, and then reheated and once again pumped onto the object beingtreated.

U.S. Pat. No. 1,608,635 to Theriot discloses a similar portableapparatus for removing paint wherein a stripping solution is heated andpumped into a discharge line for spraying onto the object to be strippedwith such object being placed on an inclined platform having a gutterleading therefrom which returns spent solvent to a receiving tank on theportable unit.

U.S. Pat. No. 2,419,397 to Frohoff et al. discloses a stationaryspraying rack for railway cars. Such rack generally forms a housinghaving a track running therethrough such that the railway car may bepositioned therein and sprayed down with hot alkaline solution. Thespent cleaning solution is then drained from the floor of the rack anddelivered to a reconditioning tank. Similarly, the more recent U.S. Pat.No. 4,378,755 to Magnusson et al. discloses a stationary housing forde-icing and cleaning airplanes. The airplane to be cleaned is slowlytaxied through the housing wherein it is sprayed with a de-icing orcleaning solution. The spent solution is removed by draining ductsformed in the floor of the housing and collected in a tank forsubsequent purification.

Generally, early prior art patents directed to methods for strippingpaint from objects have employed heating a stripping solution. Whilesome present day paint solvents are heated for use, others are employedat room temperatures. The primary component of many popular paintstrippers, methylene chloride, has a boiling point of 40° C. or 106° F.and is generally used at room temperatures. Such low boiling point,coupled with a correspondingly high vapor pressure, accounts for thecontaminating fumes common to paint stripping operations which, asdiscussed above, endanger not only the workers involved but also othersin the area. And, paint strippers which are heated for use, althoughliquid at room temperature, similarly form noxious fumes upon heating tostripping temperatures. However, such fumes are often readily dispersed.But, because methylene chloride vapor is heavier than air, the fumesgenerated thereby are not readily dispersed, but rather tend to remainlow, being trapped by the air.

Examples of portable units known for use in removing coatings fromairplanes are U.S. Pat. No. 2,733,723 to Whitcomb and U.S. Pat. No.4,146,044 to Dow, both of which are directed to cleaning the innersurfaces of airplane fuel tanks and do not address the problems ofremoving paint or grease from the large exterior surfaces of theairplane. Such task is generally performed by spraying such surfaces ina hangar with the fumes dispersed by fans and the spent liquid solventcollected on the hangar floor for subsequent clean up. Although it isgenerally known to provide troughs or gutters under the airplane edgesto catch the liquid solvent which drips therefrom, thereby facilitatingthe clean-up phase of the stripping job, there is no known prior artmethod for trapping or containing the hazardous solvent fumes generatedduring stripping. Further, there is no known prior art method forcollecting and re-processing such fumes for subsequent re-use as asolvent.

DISCLOSURE OF INVENTION

The present invention recognizes and addresses the foregoingdisadvantages, and others, of prior art paint stripper collectionsystems. Accordingly, it is one general object of the present inventionto provide an improved paint solvent collection apparatus, system, andmethod.

Another object is the provision of a method for stripping paint fromairplanes which will significantly reduce the concentration of toxicchemicals, in both the liquid and gas phases, dispersed during suchoperation.

It is yet another object of the present invention to provide anapparatus for use in paint stripping which decreases the clean uprequired after stripping.

It is a still further object of the present invention to provide asystem for use in paint stripping which employs interconnectedindividual units such that objects of any size or shape may beaccommodated.

It is a still further object of the present invention to provide amethod for stripping paint from the upper portion of airplanes whichdoes not allow dissolved paint to run onto unpainted lower surfaces.

It is yet another object of the present invention to provide a systemfor use during the stripping of paint from airplanes which reduces theconcentration of toxic methylene chloride fumes generated in thestripping operation.

These as well as other objects are achieved by providing an apparatusfor use in the removal of coatings from airplanes and the like, theremoval requiring the application of a solvent composition to thesurfaces of an airplane for dissolving or bond releasing of a coatingsuch as paint and the like thereon, the solvent composition having asufficiently high vapor pressure to be present in both a liquid phaseand a gaseous vapor phase at operating temperatures, the solvent in thevapor phase being lighter than the liquid phase and heavier than air,with the apparatus including a portable carriage positionable beneaththe airplane, a receptacle having spaced side walls and carried by thecarriage, the side walls extending vertically upwardly, the receptaclefurther defining a bottom portion, the receptacle receiving spentsolvent in both the liquid and the vapor phases after application of thesolvent to the airplane surfaces, and dissolution of the paint therein,the side walls directing the received spent solvent in both phases tothe bottom portion such that the vapor phase is trapped above theheavier liquid phase on the bottom portion by the lighter air thereover,and an exhaust port located above the bottom portion for removing thevapor phase.

Preferably, the side walls of the receptacle diverge outwardly from thebottom portion. Most preferably, a drain means is provided at thereceptacle bottom-portion for removing the spent solvent in the liquidphase.

More particularly, the present objects are achieved by providing acollection system for use in the removal of coatings from airplanes andthe like, the removal requiring the application of a solvent compositionto the surfaces of an airplane for dissolving or bond releasing acoating such as paint and the like thereon, the solvent compositionhaving a sufficiently high vapor pressure to be present in both a liquidphase and a gaseous vapor phase at stripping temperatures, the solventin the vapor phase being lighter than the liquid phase and heavier thanair, the system including a plurality of spent solvent collection units,each unit having a portable carriage positionable beneath the airplane,a receptacle having spaced side walls and carried by the carriage, theside walls extending vertically upwardly, the receptacle furtherdefining a receptacle bottom portion, the receptacle receiving spentsolvent in both the liquid and the vapor phases after application of thesolvent to the airplane surfaces, and dissolution of the paint therein,the side walls directing the received spent solvent in both phases tothe bottom portion such that the vapor phase is trapped above theheavier liquid phase on the bottom portion by the lighter air thereover,and an exhaust port located above the bottom portion for removing thevapor phase, the system further including connection means forinterconnecting the spaced side walls of the receptacles therebyinterconnecting the collection units such that a continuous solventreceiving means is formed along the length and width of theinterconnected units.

Preferably, such collection system further includes a vapor receivingunit with suction lines extending therefrom and communicating with theexhaust ports of the interconnected spent solvent collection units fordrawing the solvent in the vapor phase from the collection units to thevapor receiving unit, the vapor receiving unit further including achiller for lowering the temperature of the received solvent in thevapor phase sufficiently to condense same to the liquid phase.

More particularly, the present objects are achieved by providing acollection system for use in the removal of coatings from airplanes andthe like, the removal requiring the application of a solvent compositionto the surfaces of an airplane for dissolving a coating such as paintand the like thereon, the solvent composition having a sufficiently highvapor pressure to be present in both a liquid phase and a gaseous vaporphase at stripping temperatures, the solvent in the vapor phase beinglighter than the liquid phase and heavier than air, such systemincluding a plurality of spent solvent collection units, each unithaving a portable carriage positionable beneath the airplane, areceptacle having spaced side walls and carried by the carriage, theside walls extending vertically upwardly, the receptacle furtherdefining a bottom portion, the receptacle receiving spent solvent inboth the liquid and the vapor phases after application of the solvent tothe airplane surfaces and dissolution of said paint therein, the sidewalls directing the received spent solvent in both phases to the bottomportion, such that the vapor phase is trapped above the heavier liquidphase on the bottom portion by the lighter air thereover, an exhaustport located above the bottom portion for removing the vapor phase, anda drain means at the receptacle bottom portion for removing the spentsolvent in the liquid phase, such system further including connectionmeans for interconnecting the spaced side walls of the collection unitssuch that a continuous solvent receiving means is formed along thelength and width of the interconnected units.

It is preferred that such collection system further includes a vaporreceiving unit having suction lines extending therefrom andcommunicating with the exhaust ports of the interconnected spent solventcollection units for drawing the solvent in the vapor phase from thecollection units to the vapor receiving unit, such vapor receiving unitfurther including a chiller for lowering the temperature of the receivedsolvent in the vapor phase sufficiently to condense same to a liquidphase. Moreover, such system preferably also includes a liquid solventreceiving unit associable with each of the drain means for collectingthe solvent in the liquid phase from the bottom portions of thecollection units.

Most preferably, the present objects are achieved through a method forremoving paint from airplanes and the like using a solvent fordissolving the paint, the solvent having a sufficiently high vaporpressure to be present in both a liquid and a gaseous vapor phase atstripping temperatures, the solvent in the vapor phase being lighterthan the liquid phase and heavier than air, such method including thesteps of providing a plurality of solvent receptacles, positioning thereceptacles beneath the airplane, interconnecting the receptacles atspaced side walls thereof, thereby forming a continuous solventreceiving means, stripping the paint from the surfaces of the airplaneby applying the solvent thereto, receiving spent solvent in both theliquid and the vapor phases in the continuous solvent receiving means,directing the received spent solvent in both phases to bottom portionsdefined in the various interconnected receptacles such that solvent inthe vapor phase is trapped above the heavier liquid phase by the lighterair thereover at the various bottom portions of the interconnectedreceptacles and removing the vapor phase from the receptacles throughexhaust ports located above the receptacle bottom portions.

In a most preferred embodiment, a method is provided for removing paintfrom upper surfaces of airplanes and the like using a solvent fordissolving or bond releasing the paint, the solvent having asufficiently high vapor pressure to be present in both a liquid and agaseous vapor phase at stripping temperatures, the solvent in the vaporphase being lighter than the liquid phase and heavier than air, themethod including the steps of providing a plurality of solvent receivingreceptacles, positioning the receptacles beneath the airplane,interconnecting the receptacles at spaced side walls thereof, therebyforming a continuous solvent receiving means, securing the flexiblesheet to the surfaces of the airplane below the upper surfaces to bestripped, such that lower edges of the sheet extend downwardly into thecontinuous solvent receiving means formed by the interconnectedreceptacles, stripping the paint from the upper surfaces of the airplaneby applying the solvent thereto, directing spent solvent in both theliquid and the vapor phases from the upper surfaces of the airplanedownwardly to the spent solvent receiving means with the downwardlyextending sheet, receiving spent solvent in both the phases in thecontinuous solvent receiving means, directing the received spent solventin both phases Go bottom portions defined in the various receptaclesforming the continuous solvent receiving means such that solvent in thevapor phase is trapped above the heavier liquid phase by the lighter airthereover at the various bottom portions of the interconnectedreceptacles, and removing the vapor phase from the receptacles throughexhaust ports located above the receptacle bottom portions.

By either method, it is preferable to also include the steps ofcollecting the spent solvent in the vapor phase removed from the variousexhaust ports of the interconnected receptacles and chilling thecollected spent solvent in the vapor phase to condense same to a liquidphase. Furthermore, it is preferred to include the step of collectingspent solvent in the liquid phase from the receptacle bottom portions.Most preferably, the stripping step of the present methods is performedat room temperature.

BRIEF DESCRIPTION OF DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, to one of ordinary skill in the art, is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures, in which:

FIG. 1 is a perspective view of an airplane, having a plurality ofcollection units in accordance with the present invention interconnectedand positioned along edges thereof;

FIG. 2 is a schematic diagram of one embodiment of the receptacle of thepresent invention positioned beneath an edge of an airplane;

FIG. 3 is a schematic diagram of receptacles in accordance with thepresent invention positioned beneath opposite sides of an airplane withflexible sheets secured to the airplane extending downwardly into thereceptacles to direct the flow of paint stripper;

FIG. 4 is a schematic diagram illustrating a receptacle in accordancewith the present invention positioned under an edge of an airplane witha flexible sheet extending downwardly from the lowermost portion of thefuselage directing the flow of paint stripper into the receptacle;

FIG. 5 is a side view of an airplane having a plurality of collectionunits in accordance with the present invention interconnected andpositioned at an edge thereof;

FIG. 6 is a close-up view of a portion of an airplane havinginterconnected units positioned at a side thereof with a flexible sheetsecured to the plane at a midportion extending downwardly into thereceptacles of the collection units for directing the flow of paintstripper thereinto;

FIG. 7 is a cross-sectional schematic view of a trough of FIG. 6 witharrows representing the flow of paint stripper from the surface of theplane into the receptacle;

FIG. 8 is a top view of a plurality of interconnected collection unitsin accordance with the present invention positioned beneath an airplanewing shown in phantom;

FIG. 9 is a cross-sectional view taken along the line 9--9 of FIG. 8;

FIG. 10 is a cross-sectional schematic diagram of a pair of collectionunits interconnected below the fuselage of an airplane;

FIG. 11 illustrates one means for interconnecting collection units inaccordance with the present invention; and

FIG. 12 is a schematic diagram of a vapor collection system inaccordance with the present invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

MODES FOR CARRYING OUT THE INVENTION

It is to be understood by those of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstructions.

Referring to FIG. 1, an airplane 108 is illustrated having a pluralityof units generally 110 positioned thereabout. Such units partially makeup the present collection system generally 150 of the present invention.

Each unit is an apparatus in accordance with the present invention foruse in the removal of coatings from large objects. Specifically, thepresent invention is directed to the removal of paint from airplanes.However, it is also within the scope of the present invention to removeother coatings, such as grease and dirt, from airplanes with theapparatus and system of the present invention. Furthermore, it is alsowithin the scope of the invention to remove such coatings from otherlarge objects, such asfreight cars, ships, etc. employing the presentapparatus, system and method. However, to facilitate understanding, thepresent description is particularly directed to the removal of paintfrom large airplanes.

Such paint stripping operation generally requires the application of asolvent composition to the surfaces of the airplane for dissolving thepaint thereon. Generally, the solvent employed has a sufficiently highvapor pressure to be present in both liquid phase and a gaseous vaporphase at stripping temperatures. Thus, solvent compositions containingcomponents such as methylene chloride, which have a sufficiently highvapor pressure at room temperature to exist as both a liquid and a vaporand which are employed at room temperature in stripping operations, arewithin the scope of the present invention. Also with the scope of thepresent invention are those solvents which, although present as a liquidat room temperature, are heated for stripping, with such heatingincreasing the vapor pressure of the solvent such that it exists as bothaliquid and a vapor at stripping temperatures.

Furthermore, solvents which do not fume at the stripping temperature,whether that temperature is room temperature or higher, may also becollected by the apparatus and system of the present invention. However,it will be understood from the present discussion that such apparatusand system are specifically designed to address the particular problemsof collecting spent solvent which has a sufficiently high vapor pressureat operating temperature to exist as both a liquid and a gas.

Referring to the figures of the drawings, it will be noted that eachfiguregenerally illustrates the apparatus or system of the presentinvention. As each figure illustrates and emphasizes variousmodifications of specific features, all within the scope of the presentinvention, features which are the same or similar from one figure to thenext are generally represented by like hundred series numbers, suchthat, for example, receptacle 120 of FIG. 1 is analogous to thereceptacle 220 of FIG. 2 and the receptacle 320 of FIG. 3, etc.

Thus, referring to FIG. 1, the apparatus 110 of the present inventionincludes a portable carriage 112 which is positionable beneath theairplane 108. The carriage includes lower frame 114 and wheels orcasters 116, although, of course, other means for moving the carriagesuch as, forexample, sliding or rail engaging members, are also withinthe scope of thepresent invention.

A receptacle 120 is carried on the carriage and includes spaced sidewalls 122 and 124. Generally, such side walls extend vertically upwardlywith lower portions thereof being joined by a lower wall 126. Thereceptacle further defines a receptacle bottom portion which, in thepresent case, isthe bottom 127 of collection tank 128. Tank 128, whichis preferably defined at the center of receptacle 120, includes tankside walls 129. Thereceptacle side walls and opposed lower walls 126extend outwardly and upwardly from upper portions of such tank sidewalls with the receptacle side walls preferably further divergingoutwardly from the receptacle lower wall.

Although in the present embodiment the receptacle bottom portion is atthe bottom of tank 128, it is to be understood that the receptaclebottom portion may be generally formed by the intersection at thelowermost pointof the receptacle of the side walls with the lower wall,or, in the case ofa receptacle which defines no specific lower wall, bythe intersection at the lowermost point of the receptacle of side wallswhich are joined at and diverge from lower portions thereof.

Thus, spent solvent in both liquid and gas phases falling from thesurfacesof the airplane 108 is received by receptacle 120 having sidewalls 122 and124 which preferably diverge outwardly as well as extendingupwardly in order to direct the received spent solvent in both phases tothe receptacle bottom portion. In the present embodiment, such bottomportion is defined at the bottom of a collection tank in which thesolvent is received such that the vapor phase of the solvent is trappedabove the heavier liquid phase by the lighter air thereover. Althoughnot specifically shown in the illustration of FIG. 1, an exhaust port islocated above the receptacle bottom portion, and therefore, in thepresentembodiment, above the bottom of the collection tank, for removingthe vaporphase.

Alternative receptacle configurations are illustrated in FIGS. 2, 3 and4 with the fuselage of the airplane schematically represented at 208,308 and 408, respectively. The receptacle 220 of FIG. 2 defines sidewalls 222and 224 which extend vertically upwardly and are joined atlower portions thereof by lower wall 226. The respective side walls ofsuch receptacle diverge greatly from the lower wall and are of variableheight, with wall 222 extending upwardly to more than twice the heightof wall 224. Thus, the receptacle may be positioned further under theedge of the fuselage than is possible with the receptacle of FIG. 1because of the abbreviated nature of the inner side wall 224. Outer wall222 extends upwardly beyond the top of wall 224 to prevent splatteringof liquid solvent as it is received by the receptacle.

FIG. 3 illustrates a pair of receptacles 320 having side walls 322 and324 extending vertically upwardly from a lower wall 326. While divergingfrom such lower wall, the side walls of FIG. 3 do not diverge as greatlyas those of FIGS. 1 and 2 discussed above. However, like the embodimentof FIG. 2, the inner side walls 324 extend upwardly to only one-half theheight of outer side walls 322 such that the receptacle may bepositioned beneath the edge of fuselage 308 with the outer side wallshaving sufficient height to preclude splattering of liquid solventfalling from the fuselage surfaces. FIG. 3 further illustrates flexiblesheets 340 extending downwardly from the fuselage to direct the flow ofspent solventin the liquid and vapor phases into receptacle 320. Thefunction of such flexible sheet will be discussed in greater detailbelow with respect to FIGS. 6 and 7.

FIG. 4 illustrates yet another embodiment of the receptacle inaccordance with the present invention with upstanding side wall 422greatly exceedingthe height of abbreviated side wall 424 such thatreceptacle 420 may be positioned beneath fuselage 408 and extended morethan halfway thereunder.Flexible sheet 440 is attached to and extendsdownwardly from the midpoint of the underside of fuselage 408 fordirecting spent solvent in the liquidand gas phases into receptacle 420.

The function of such flexible sheets with respect to the presentinvention is best understood from FIGS. 6 and 7 with FIG. 6 generallyillustrating asystem 650 of individual unit 610 in accordance with thepresent invention having portable carriages 612 each having a lowerframe 614 and wheels 616and with each carriage further having upstandingsupport members 618 for supporting the receptacle 620.

Flexible sheet 640 is secured to airplane 608 by tape 642. By the methodofthe present invention, the upper surfaces of an airplane may bestripped without spent solvent having dissolved paint components thereinbeing allowed to run down onto lower surfaces. Such is often desirablewhen onlythe upper surfaces of the airplane are painted, as is the casewith some commercial airlines, and it is preferable to keep solvent anddissolved paint from running onto the lower unpainted surfaces. Thus, bythe presentmethod, a flexible sheet is secured to the fuselage of theairplane below the upper surfaces to be stripped and extends downwardlyinto the receptacle for protecting the lower surfaces and for directingspent solvent in both the liquid and gas phases into the receptacle.

Accordingly, by the embodiment of FIG. 6, spent solvent flowing from theupper surfaces of airplane 608 is directed by flexible sheet 640 intothe receptacle 620. The side walls of the receptacle in combination withinwardly inclined lower walls 626 direct the solvent to the receptaclebottom portion at the bottom of collection tank 628. FIG. 6 furtherillustrates a drain means 630 at the bottom of the collection tank.Again,it should be understood that the collection tank, althoughpreferred, is not required and that such drain means provided at thebottom portion of the receptacle will allow for drainage of spentsolvent in the liquid phase therefrom whether such bottom portion isdefined at a collection tank bottom or merely at the lowermost portionof a receptacle which does not include such tank.

By the embodiment of FIG. 7, the receptacle 720 is supported by sidewalls 719 of the carriage. Thus, such side walls in combination with asolid bottom frame 714 form the collection tank 728, and therefore, thebottom portion of the receptacle 720 is at the bottom 727 of tank 728.Thus, drain port 730 is provided at bottom 727 with exhaust port 732positioned above bottom 727 for removing the spent solvent in the vaporphase. Suction line 734 and the vapor collection system of which it is apart will be discussed in greater detail below with respect to FIG. 12.

Thus, as is best shown in FIGS. 1, 5 and 6, a collection system inaccordance with the present invention includes a plurality of individualunits interconnected by a connection means such that a continuoussolvent receiving means is formed. FIG. 6 best illustrates one suchconnection means wherein side and lower walls of the receptacle includetelescoping portions represented by outwardly extending member 622' ofthe adjacent side walls 622. Although not shown in FIG. 6, lower wall626 and inner side wall 624 also include outwardly extending telescopingmembers which may be integral with member 622' such that an outwardlytelescoping sleeveis formed at opposite ends of each receptacle. Suchsleeve, generally nested within the receptacle in a closed position, mayslide outwardly therefrom to an open position. Preferably, such sleeve,when pulled out tosaid open position is not rigidly aligned with theside walls and bottom portion of the receptacle, but rather hassufficient flexibility or freedom of movement to allow two adjacentopened sleeves extending from adjacent receptacles of identical heightto be telescoped and positioned one over the other while maintaining acontinuous solvent receiving means which precludes solvent spillage.

In addition to such end-to-end connection, it is preferable that thepresent system includes a means for side-by-side connection of thevariousunits. Such is desirable, as in the embodiment of FIG. 10, wheretwo units are connected side by side in order to form a spent solventreceiving means beneath airplane 1008. FIG. 11 illustrates one means forachieving such side-by-side connection wherein a jacking means 1158 isincluded on carriage 1112 for tilting the receptacle carried thereonsuch that rolled edges 1160 and 1160' carried at the upper portions ofadjacent side walls 1122 and 1124' may be brought into contact foroverlapping securement as is best illustrated in FIG. 10. It shouldgenerally be noted that the casters 1116 of unit 1110 will allow same tobe moved closer to unit 1110'upon securement of rolled edge 1160 withinrolled edge 1160'. It should further be noted that rolled edge 1160' isslightly larger than rolled edge 1160 to allow for nesting of rollededge 1160 therein. Thus, each receptacle to be connected by the presentmeans must carry one large rolled edge on one side wall and a smallerrolled edge on the opposite side wall.

Such side-by-side connection is also important when it is necessary tostrip paint, not only from the fuselage, but also from the wings of theairplane. FIG. 8 illustrates a series of units of varying lengthconnectedin side by side arrangement for receiving spent solvent fromwing 807 shownin phantom. Looking to one unit, 810 of that figure, sidewalls 822 and 824are joined by lower wall 826. The receptacle furtherdefines at a midportion thereof a collection tank 828. The side wallsextend verticallyupwardly from the lower wall and, together with thelower wall, extend upwardly from the collection tank as is best seenfrom the cross-sectionalside view of FIG. 9 which shows wall 822extending outwardly and upwardly from collection tank 828. Thereceptacle 820 is carried on carriage 812 having lower frame 814 andwheels 816 and is specifically supported by upstanding members 818 ofthe carriage.

The solvent collection system of the present invention most preferablyfurther includes a vapor collection means for collecting the solventvapors trapped by air above the spent liquid solvent at the bottomportions of the various receptacles. FIG. 12 schematically illustrates apreferred embodiment of such vapor collection means wherein suctionlines 1234 are associable with exhaust ports 1232 defined above thebottom portions of the receptacles for removing the solvent vapor phasetherethrough. Preferably, individual suction lines 1234 communicate withacentral suction line 1235 which further communicates with a vaporreceivingunit 1236. In addition to a means for generating suction suchas a pump, vapor receiving unit 1236 further includes a chiller 1237 forlowering thetemperature of the received solvent vapor sufficiently tocondense such vapor to the liquid phase. Generally, such condensedliquid solvent is of adequate purity for immediate reuse.

Similarly, the present system also preferably further includes a liquidsolvent collection means. However, the liquid solvent collected by suchmeans, such as liquid solvent receiving unit 170 of FIG. 1, is notsufficiently pure for subsequent use absent purification for separationofsolvent from the paint and dirt particles dissolved therein. Further,although a centralized liquid collection system having a series of drainlines, analogous to the vapor collection means discussed above, iswithin the scope of the present invention, a single mobile unit such asunit 170 having drain line 172 associable with the drain ports of thevarious receptacles, is preferred. Thus, the receptacles are notcontinuously drained by a centralized system but are individuallydrained as the liquidsolvent level of each separate unit becomes toohigh. Generally, the liquidsolvent level of a given receptacle becomestoo high as it approaches the level of the exhaust port of thatreceptacle. Suction of the liquid solvent through the exhaust port andto the vapor receiving unit will contaminate the relatively pure liquidphase therein which has been condensed from solvent vapors. Thus, thevarious receptacles are drained as needed by unit 170 with the spentliquid solvent being collected by such unit for subsequent purificationand eventual reuse.

The present invention encompasses not only the individual units andcollection system discussed above but a method for removing paint fromairplanes and the like. The present method is specifically directed tostripping operations involving a solvent having a sufficiently highvapor pressure to be present in both the liquid and vapor phases atstripping temperature, whether such temperature is room temperature orhigher. Specifically, the present method addresses the particularproblems of stripping large objects with a solvent having fumes whichare not readily dissipated but, rather, are heavier than air and,therefore, tend to remain low endangering workers and others in thearea.

The steps of such method include providing a plurality of portablesolvent receiving receptacles and positioning such receptacles beneaththe airplane. The receptacles are than interconnected to form acontinuous solvent receiving means which avoids dripping of spentsolvent to the floor between adjacent receptacles. The solvent is thenapplied to the surfaces of the airplane, preferably at room temperature,for stripping the paint thereon. Spent solvent in both phases fallingfrom the surfaces of the airplane is received in the continuous solventreceiving means formed by the interconnected receptacles. Receivedsolvent is directed with such solvent receiving means to bottom portionsof the various receptacles at which the lighter vapor phase is trappedabove the heavier liquid phase by the lighter air thereover. The trappedvapor phase is continuously removed from the various receptacles throughexhaust ports defined therein.

Preferably, such removed vapor is collected at a centralized locationand chilled to condense same to the liquid phase. The spent liquid phasein the various receptacles is also collected for subsequentpurification.

The present method is also adaptable for use in the removal of paintfrom the upper surfaces only of airplanes. It is common among somecommercial airliners and private owners to paint only the top half ofairplanes. Whenstripping the paint from such top surfaces it isobviously preferred that spent solvent having paint and dirt particlesdissolved therein not be allowed to drip onto the lower unpaintedsurfaces such that, in essence, the entire airplane must be stripped assuch lower surfaces are stained bythe dripping dissolved paint. Thus,the present method may further include the step of securing a flexiblesheet, such as polyethylene, to the surfaces of the airplane below theupper surfaces to be stripped such thatlower edges of the sheet extenddownwardly into the continuous solvent receiving means formed by theinterconnected receptacles. During strippingsuch sheet serves to protectthe lower unpainted surfaces from dripping spent solvent. Further, suchsheet also aids in directing the spent solvent in both the liquid andvapor phases downwardly into the spent solvent in both the liquid andvapor phases downwardly into the spent solvent receiving means. Thus, itmay occasionally be preferred to providesuch a sheet merely for itsdirecting function even when specific surfaces do not requireprotection. Such is illustrated in the schematic diagram ofFIG. 4wherein a single sheet 440 is attached to the lowermost surface ofairplane 408 such that spent solvent may flow therealong into receptacle420.

These and other modifications and variations to the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting fromthe spirit and scope of the present invention, which ismore particularly set forth in the appended claims. Furthermore, thoseof ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to belimitative of the invention so further described in such appendedclaims.

Thus, for the present invention, features illustrated or described aspart of one embodiment can be used on another embodiment to yield astill further embodiment.

What is claimed is:
 1. An apparatus for use in the removal of coatingsfrom airplanes, said removal requiring the application of a solventcomposition to the surfaces of an airplane for dissolving a coatingthereon, said solvent composition having a sufficiently high vaporpressure to be present in both a liquid phase and a gaseous vapor phaseat stripping temperatures, said solvent in said vapor phase beinglighter than said liquid phase and heavier than air, comprising:aportable carriage positionable beneath said airplane; a receptaclehaving spaced side walls and carried by said carriage, said side wallsextending vertically upwardly, said receptacle further defining areceptacle bottom portion, said receptacle receiving spent solvent inboth said liquid and said vapor phases after application of said solventto said airplane surfaces and dissolution of said paint therein, saidside walls directing said received spent solvent in both phases to saidreceptacle bottom portion such that said vapor phase is trapped abovesaid heavier liquid phase by the lighter air thereover; and an exhaustport located above said receptacle bottom portion for removing saidvapor phase.
 2. An apparatus as set forth in claim 1 wherein said sidewalls diverge outwardly from said receptacle bottom portion.
 3. Anapparatus as set forth in claim 1 further including a drain means atsaid receptacle bottom portion for removing said spent solvent in saidliquid phase.
 4. An apparatus as set forth in claim 1 wherein saidreceptacle further defines a collection tank having said receptaclebottom portion defined at a bottom of said tank.
 5. An apparatus as setforth in claim 1 wherein said solvent compositions includes methylenechloride as a major component thereof.
 6. A collection system for use inthe removal of coatings from airplanes, said removal requiring theapplication of a solvent composition to the surfaces of an airplane fordissolving a coating thereon, said solvent composition having asufficiently high vapor pressure to be present in both a liquid phaseand a gaseous vapor phase at stripping temperatures, said solvent insaid vapor phase being lighter than said liquid phase and heavier thanair, comprising:a plurality of spent solvent collection units, each unitcomprising:a portable carriage positionable beneath said airplane; areceptacle having spaced side walls and carried by said carriage, saidside walls extending vertically upwardly, said receptacle furtherdefining a receptacle bottom portion, said receptacle receiving spentsolvent in both said liquid and said vapor phases after application ofsaid solvent to said airplane surfaces and dissolution of said painttherein, said side walls directing said received spent solvent in bothphases to said receptacle bottom portion such that said vapor phase istrapped above said heavier liquid phase by the lighter air thereover; anexhaust port located above said receptacle bottom portion for removingsaid vapor phase; and connection means for interconnecting said spacedside walls of said receptacles thereby interconnecting said collectingunits such that a continuous solvent receiving means is formed along thelength and width of said interconnected units.
 7. A collection system asset forth in claim 6 wherein said connection means includes outwardlytelescoping sleeve members carried at opposite ends of said receptacleside walls for end-to-end connection of said plurality of units.
 8. Acollection system as set forth in claim 6 wherein said connection meansincludes hooking elements defined at upper portions of said receptacleside walls for side-to-side connection of said plurality of units.
 9. Acollection system as set forth in claim 6 further including a vaporreceiving unit having suction lines extending therefrom andcommunicating with said exhaust ports of said interconnected spentsolvent collection units for drawing said solvent in said vapor phasefrom said receptacles of said collection units to said vapor receivingunit, said vapor receiving unit further including a chiller for loweringthe temperature of said received solvent in said vapor phasesufficiently to condense same to said liquid phase.
 10. A collectionsystem for use in the removal of coatings from airplanes, said removalrequiring the application of a solvent composition to the surfaces of anairplane for dissolving a coating thereon, said solvent compositionhaving a sufficiently high vapor pressure to be present in both a liquidphase and a gaseous vapor phase at stripping temperatures, said solventin said vapor phase being lighter than said liquid phase and heavierthan air, comprising:a plurality of spent solvent collection units, eachunit comprising:a portable carriage positionable beneath said airplane;a receptacle having spaced side walls and carried by said carriage, saidside walls extending vertically upwardly, said receptacle furtherdefining a receptacle bottom portion, said receptacle receiving spentsolvent in both said liquid and said vapor phases after application ofsaid solvent to said airplane surfaces and dissolution of said painttherein, said side walls directing said received spent solvent in bothphases to said receptacle bottom portion such that said vapor phase istrapped above said heavier liquid phase by the lighter air thereover; anexhaust port located above said receptacle bottom portion for removingsaid vapor phase; and drain means at said receptacle bottom portion forremoving said liquid phase; connection means for interconnecting saidspaced side walls of said receptacles thereby interconnecting saidcollection units such that a continuous solvent receiving means isformed along the length and width of said interconnected units.
 11. Acollection system as set forth in claim 10 further including a vaporreceiving unit having suction lines extending therefrom andcommunicating with said exhaust ports of said interconnected spentsolvent collection units for drawing said solvent in said vapor phasefrom said receptacles of said collection units to said vapor receivingunit, said vapor receiving unit further including a chiller for loweringthe temperature of said received solvent in said vapor phasesufficiently to condense same to said liquid phase.
 12. A collectionsystem as set forth in claim 10 further including a liquid solventreceiving unit associable with each of said drain means for collectingsaid solvent in said liquid phase from said receptacle bottom portionsof said collection units.
 13. A method for removing paint from airplanesusing a solvent for dissolving said paint, said solvent having asufficiently high vapor pressure to be present in both a liquid and agaseous vapor phase at stripping temperatures, said solvent in saidvapor phase being lighter than said liquid phase and heavier than air,comprising:providing a plurality of portable solvent receivingreceptacles; positioning said receptacles beneath said airplane;interconnecting said receptacles at spaced side walls thereof therebyforming a continuous solvent receiving means; stripping said paint fromthe surfaces of said airplane by applying said solvent thereto;receiving spent solvent in both said liquid and said vapor phases insaid continuous solvent receiving means; directing said received spentsolvent in both phases to bottom portions defined in said variousreceptacles such that solvent in said vapor phase is trapped above saidheavier liquid phase by the lighter air thereover at said various bottomportions of said interconnected receptacles; and removing said vaporphase from said receptacles through exhaust ports located above saidreceptacle bottom portions.
 14. A method as set forth in claim 13wherein said step of stripping is performed by applying a solvent havingmethylene chloride as a major component thereof to said airplanesurfaces.
 15. A method as set forth in claim 13 further includingcollecting said spent solvent in said vapor phase removed from saidvarious exhaust ports of said interconnected receptacles.
 16. A methodas set forth in claim 15 further including chilling said collected spentsolvent in said vapor phase to condense same to a liquid phase.
 17. Amethod as set forth in claim 13 further including collecting spentsolvent in said liquid phase from said receptacle bottom portions.
 18. Amethod as set forth in claim 13 wherein said step of stripping isperformed at room temperature.
 19. A method for removing paint fromupper surfaces of airplanes using a solvent for dissolving said paint,said solvent having a sufficiently high vapor pressure to be present inboth a liquid and a gaseous vapor phase at ambient temperatures, saidsolvent in said vapor phase being lighter than said liquid phase andheavier than air, comprising the steps of:providing a plurality ofsolvent receiving receptacles; positioning said receptacles beneath saidairplane; interconnecting said receptacles at spaced side walls thereofthereby forming a continuous solvent receiving means; securing aflexible sheet to the surfaces of said airplane below said uppersurfaces to be stripped such that lower edges of said sheet extenddownwardly into said continuous solvent receiving means formed by saidinterconnected receptacles; stripping said paint from said uppersurfaces of said airplane by applying said solvent thereto; directingspent solvent in both said liquid and said vapor phases from said uppersurfaces downwardly to said spent solvent receiving means with saiddownwardly extending sheet; receiving spent solvent in both said phasesin said continuous solvent receiving means; directing said receivedspent solvent in both phases to bottom portions defined in said variousreceptacles forming said continuous solvent receiving means such thatsolvent in said vapor phase is trapped above said heavier liquid phaseby the lighter air thereover at said various bottom portions of saidinterconnected receptacles; and removing said vapor phase from saidreceptacles through exhaust ports located above said receptacle bottomportions.
 20. A method as set forth in claim 19 further includingcollecting said spent solvent in said vapor phase removed from saidvarious exhaust ports of said interconnected receptacles.
 21. A methodas set forth in claim 20 further including chilling said collected spentsolvent in said vapor phase to condense same to a liquid phase.
 22. Amethod as set forth in claim 19 further including collecting spentsolvent in said liquid phase from said receptacle bottom portions.
 23. Amethod as set forth in claim 19 wherein said step of stripping isperformed at room temperature.